One formula for a person's maximum heart rate is 220 − x, where x is the person's age in years for 20 ≤ x ≤ 70. The American Heart Association recommends that when a person exercises, the person should strive for a heart rate that is at least 50% of the maximum and at most 85% of the maximum. (Source: American Heart Association)
(a) Write and graph a system of inequalities that describes the exercise target heart rate region.
(b) Find two solutions of the system and interpret their meanings in the context of the problem.
2. A warehouse supervisor has instructions to ship at least 50 bags of gravel that weigh 55pounds each and at least 40 bags of stone that weigh 70pounds each. The maximum weight capacity of the truck being used is 7500 pounds.
(a) Write and graph a system that describes the numbers of bags of stone and gravel that can be shipped.
(b) Find two solutions of the system and interpret their meanings in the context of the problem.